This should be interesting just because HUNL always is but like jeff said, not 1, 2, or even 7 HU sessions can prove the better player. I think possessed has a definite advantage over anyone who doesn't regularly play 5-10NL because others will value the money more than him. For example, if I played 25Nl HU against someone who's bankrolled for 25nl only, I think I'd kill them partly because the money there means nothing to me.